Install depot_tools

Add depot_tools to the end of your PATH (you will probably want to put this in your ~/.bashrc or ~/.zshrc). Assuming you cloned depot_tools to /path/to/depot_tools:

export PATH="$PATH:/path/to/depot_tools"

Get the code

Create a chromium directory for the checkout and change to it (you can call this whatever you like and put it wherever you like, as long as the full path has no spaces):

mkdir ~/chromium && cd ~/chromium
fetch --nohooks android

If you don't want the full repo history, you can save a lot of time by adding the --no-history flag to fetch.

Expect the command to take 30 minutes on even a fast connection, and many hours on slower ones.

If you've already installed the build dependencies on the machine (from another checkout, for example), you can omit the --nohooks flag and fetch will automatically execute gclient runhooks at the end.

When fetch completes, it will have created a hidden .gclient file and a directory called src in the working directory. The remaining instructions assume you have switched to the src directory:

cd src

Converting an existing Linux checkout

If you have an existing Linux checkout, you can add Android support by appending target_os = ['android'] to your .gclient file (in the directory above src):

echo "target_os = [ 'android' ]">>../.gclient

Then run gclient sync to pull the new Android dependencies:

gclient sync

(This is the only difference between fetch android and fetch chromium.)

Install additional build dependencies

Once you have checked out the code, run

build/install-build-deps-android.sh

to get all of the dependencies you need to build on Linux, plus all of the Android-specific dependencies (you need some of the regular Linux dependencies because an Android build includes a bunch of the Linux tools and utilities).

Run the hooks

Once you've run install-build-deps at least once, you can now run the Chromium-specific hooks, which will download additional binaries and other things you might need:

gclient runhooks

Optional: You can also install API keys if you want your build to talk to some Google services, but this is not necessary for most development and testing purposes.

Setting up the build

Chromium uses Ninja as its main build tool along with a tool called GN to generate .ninja files. You can create any number of build directories with different configurations. To create a build directory which builds Chrome for Android, run:

gn gen --args='target_os="android"'out/Default

You only have to run this once for each new build directory, Ninja will update the build files as needed.

You can replace Default with another name, but it should be a subdirectory of out.

For other build arguments, including release settings, see GN build configuration. The default will be a debug component build matching the current host operating system and CPU.

Also be aware that some scripts (e.g. tombstones.py, adb_gdb.py) require you to set CHROMIUM_OUTPUT_DIR=out/Default.

Build Chromium

Build Chromium with Ninja using the command:

autoninja -C out/Default chrome_public_apk

(autoninja is a wrapper that automatically provides optimal values for the arguments passed to ninja.)

You can get a list of all of the other build targets from GN by running gn ls out/Default from the command line. To compile one, pass the GN label to Ninja with no preceding “//” (so, for //chrome/test:unit_tests use autoninja -C out/Default chrome/test:unit_tests).

Multiple Chrome APK Targets

The Google Play Store allows apps to send customized .apk files depending on the version of Android running on a device. Chrome uses this feature to target 3 different versions using 3 different ninja targets:

Updating your checkout

To update an existing checkout, you can run

$ git rebase-update
$ gclient sync

The first command updates the primary Chromium source repository and rebases any of your local branches on top of tip-of-tree (aka the Git branch origin/master). If you don't want to use this script, you can also just use git pull or other common Git commands to update the repo.

The second command syncs dependencies to the appropriate versions and re-runs hooks as needed.

Installing and Running Chromium on a device

Plug in your Android device

Make sure your Android device is plugged in via USB, and USB Debugging is enabled.

To enable USB Debugging:

Navigate to Settings > About Phone > Build number

Click ‘Build number’ 7 times

Now navigate back to Settings > Developer Options

Enable ‘USB Debugging’ and follow the prompts

You may also be prompted to allow access to your PC once your device is plugged in.

You can check if the device is connected by running:

third_party/android_tools/sdk/platform-tools/adb devices

Which prints a list of connected devices. If not connected, try unplugging and reattaching your device.

Enable apps from unknown sources

Allow Android to run APKs that haven't been signed through the Play Store:

Enable ‘Unknown sources’ under Settings > Security

In case that setting isn't present, it may be possible to configure it via adb shell instead:

Testing

Faster Edit/Deploy

GN Args

What it does: Uses multiple .so files instead of just one (faster links)

is_java_debug = true(default=is_debug)

What it does: Disables ProGuard (slow build step)

enable_incremental_javac = true(default=false)

What it does: Tries to compile only a subset of .java files within an android_library for subsequent builds.

Can cause infrequent (once a month-ish) failures due to not recompiling a class that should be recompiled.

Incremental Install

“Incremental install” uses reflection and side-loading to speed up the edit & deploy cycle (normally < 10 seconds). The initial launch of the apk will be a little slower since updated dex files are installed manually.

To avoid typing _incremental when building targets, you can use the GN arg:

incremental_apk_by_default = true

This will make chrome_public_apk build in incremental mode.

Installing and Running Chromium on an Emulator

Running on an emulator is the same as on a device. Refer to android_emulator.md for setting up emulators.

Tips, tricks, and troubleshooting

Rebuilding libchrome.so for a particular release

These instructions are only necessary for Chrome 51 and earlier.

In the case where you want to modify the native code for an existing release of Chrome for Android (v25+) you can do the following steps. Note that in order to get your changes into the official release, you'll need to send your change for a codereview using the regular process for committing code to chromium.